Created attachment 186431 [details]
Patch adding the dc5750 to the list of radeon rs4xxx quirks

The HP Compaq dc5750 is unable to resume from the suspend state. With the system suspended and I press the power button on the front of the machine I expect it to wake up. When the button is pressed the HDD and CD drive lights activate briefly and the fan powers on. The video output does not appear to resume and stays black. I have to hard power the system to bring it back. Attempting to suspend/resume has this issue every time I have tried it.

I observed this behavior on kernels 4.1.6 and 4.0.5.

Setting devices in /sys/power/pm_debug resulted in the system failing to resume.
The freezer method in /sys/power/pm_debug did not have an issue resuming.

I enabled /sys/power/pm_trace and after the hard boot I was able to find a reasonable hash matches line: ' pci 0000:01:05.0: hash matches'. Additionally /sys/power/pm_trace_dev_match was able to resolve this to `radeon`.

I was able to boot using a serial console and prevented the radeon driver from loading. In this state it was able to suspend and resume properly. From this state I let the radeon driver load again and the system would fail to resume from suspend.

I was able to add this system to the list of RS480 quirks. The system was able to suspend and resume normally with the change. It worked with the Xserver running as well. It appears to be running normally. I have attached the patch I tested against the 4.0.5 and 4.1.6 kernels.

Is there anything else I should test?